Device for processing a substrate, method of processing a substrate and method of manufacturing semiconductor device

ABSTRACT

Provided is a substrate processing apparatus and a method of manufacturing a semiconductor device, which are hard to cause a defect in processing a substrate owing to that a pressure inside a process chamber is not kept constant, and which enable a better processing of a substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of application Ser. No. 12/225,118 filed Oct. 3,2008, which in turn is a National Phase of PCT/JP2007/062594 filed Jun.22, 2007, which in turn claims the benefit of Japanese Application No.JP 2006-178022, filed Jun. 28, 2006. The disclosure of the priorapplications is hereby incorporated by reference herein in its entirety.

BACKGROUND

The present invention relates to a substrate-processing device forperforming a process of a substrate including oxidization of a substratesurface of a semiconductor wafer, a glass substrate and the like, and amethod of manufacturing a semiconductor device including the step ofperforming such process of a substrate.

A technique used for a substrate-processing device and asubstrate-processing method of this type has been known, and thetechnique includes a process chamber for processing a substrate, asupplying line for supplying a reactive gas into the process chamber,and an exhaust line for exhausting the process chamber.

SUMMARY

However, conventionally in the step of performing a treatment e.g.thermal oxidization of a surface of a substrate, the differentialpressure between a pressure of the inside of a process chamber and apressure of the outside of the process chamber is measured, and thepressure inside the process chamber is controlled based on a result ofthe measurement. Therefore, it has been difficult to keep the pressureinside the process chamber constant because when the pressure of theoutside of the process chamber is changed by e.g. a climate change, theinside pressure of the process chamber is changed with this change.There has been a problem such that e.g. the variation in thickness of anoxide film owing to thermal oxidization arises, and thus a substratecannot be processed well.

The invention aims to provide a substrate-processing device and a methodof manufacturing a semiconductor device, which are hard to cause adefect in processing a substrate owing to that a pressure inside aprocess chamber is not kept constant, and which enable a betterprocessing of a substrate.

According to an embodiment of the invention is provided asubstrate-processing device including: a process chamber for processinga substrate; a reactive gas-supplying module for supplying a reactivegas into the process chamber; a reactive gas-supplying line forsupplying the reactive gas from the reactive gas-supplying module intothe process chamber; an exhaust line for exhausting the process chamber;a pump provided on the exhaust line for vacuumizing inside the processchamber; a pressure-adjusting valve provided in the exhaust line foradjusting a pressure in the process chamber; a first pressure-measuringinstrument for measuring a pressure of an inside of the process chamber;a second pressure-measuring instrument for measuring a differentialpressure between the inside pressure of the process chamber and anoutside pressure thereof; and a controller which controls thepressure-adjusting valve based on a value of the inside pressure of theprocess chamber measured by the first pressure-measuring instrument soas to keep the inside pressure of the process chamber constant, andcontrols the reactive gas-supplying module based on a value of thedifferential pressure measured by the second pressure-measuringinstrument so as to allow supply of the active gas into the processchamber in a case of the inside pressure of the process chamber beingsmaller than the outside pressure thereof, and so as to preclude supplyof the reactive gas into the process chamber in a case of the insidepressure of the process chamber being larger than the outside pressurethereof when processing the substrate.

According to another embodiment of the invention is provided asubstrate-processing device including: a process chamber for processinga substrate; a reactive gas-supplying line for supplying a reactive gasinto the process chamber; an exhaust line for exhausting the processchamber; a pump provided on the exhaust line for vacuumizing inside theprocess chamber; a pressure-adjusting valve provided in the exhaust linefor adjusting a pressure in the process chamber; a firstpressure-measuring instrument for measuring a pressure of an inside ofthe process chamber; a second pressure-measuring instrument formeasuring a differential pressure between the inside pressure of theprocess chamber and an outside pressure thereof; a lid for hermeticallyclosing an opened portion of the process chamber to take in and out thesubstrate; and a controller which controls the pressure-adjusting valvebased on a value of the inside pressure of the process chamber measuredby the first pressure-measuring instrument so as to keep the insidepressure of the process chamber constant when processing the substrate,and after the processing of the substrate, performs control based on thevalue of the differential pressure measured by the secondpressure-measuring instrument so that disablement of the hermeticallyclosing by the lid is allowed when the differential pressure fallswithin an allowable range, and so that disablement of the hermeticallyclosing by the lid is precluded when the differential pressure fallsoutside the allowable range.

According to still another embodiment of the invention is provided amethod of manufacturing a semiconductor device including the steps of:bringing a substrate into a process chamber; processing the substratewhile supplying a reactive gas into the process chamber with thesubstrate brought therein and vacuumizing inside the process chamber;and bringing out the processed substrate from the process chamber,wherein the step of processing the substrate includes measuring apressure of an inside of the process chamber, and in parallel, keepingthe inside pressure of the process chamber constant based on ameasurement thereof, and measuring a differential pressure between theinside pressure of the process chamber and an outside pressure thereof,and based on a measurement thereof, supplying the reactive gas into theprocess chamber when the inside pressure of the process chamber issmaller than the outside pressure thereof, provided that when the insidepressure of the process chamber is larger than the outside pressurethereof, the reactive gas is not supplied into the process chamber.

Further, according to another embodiment of the invention is provided amethod of manufacturing a semiconductor device including the steps of:bringing a substrate into a process chamber; processing the substratewhile supplying a reactive gas into the process chamber with thesubstrate brought therein and vacuumizing inside the process chamber;and bringing out the processed substrate from the process chamber,wherein the step of processing the substrate includes measuring apressure of an inside of the process chamber, and in parallel, keepingthe inside pressure of the process chamber constant based on ameasurement thereof, and after the processing of the substrate,measuring a differential pressure between the inside pressure of theprocess chamber and an outside pressure thereof, and the step ofprocessing the substrate includes, depending on a measurement thereof,bringing out the processed substrate when the differential pressurefalls within an allowable range, whereas when the differential pressurefalls outside the allowable range, the step of bringing out theprocessed substrate is not executed.

The invention provides a substrate-processing device and a method ofmanufacturing a semiconductor device, which are hard to cause a defectin processing a substrate owing to that a pressure inside a processchamber is not kept constant, and which enable a better processing of asubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a substrate-processing deviceaccording to an embodiment of the invention.

FIG. 2 is a set of explanatory views showing a configuration of areactive gas-supplying device used in the embodiment of the invention,of which the portion (a) is an explanatory view for explaining aconfiguration for supplying a gas of water vapor produced by combustionof a gaseous mixture containing hydrogen gas and oxygen gas, the portion(b) is an illustration for explaining a configuration for supplying agaseous mixture of oxygen and at least not less than one kind of gasselected from a group consisting of nitrogen gas, hydrogen chloride anddichloroethylene, and the portion (c) is an illustration showing aconfiguration for supplying a gaseous mixture of oxygen, hydrogen and atleast not less than one kind of gas selected from a group consisting ofnitrogen gas, hydrogen chloride and dichloroethylene.

FIG. 3 is an explanatory view showing a configuration of apressure-control device used in the embodiment of the invention.

FIG. 4 is a block diagram showing a controller used in the embodiment ofthe invention.

FIG. 5 is a flowchart showing a control flow of the controller used inthe embodiment of the invention.

FIG. 6 is a graph showing the relation between the pressure of theatmospheric pressure and the film thickness of an oxide film formed on asubstrate in the case of using the substrate-processing device accordingto the embodiment of the invention to perform an oxidization process.

FIG. 7 is a graph showing the relation between the atmospheric pressureand the film thickness of an oxide film formed on a substrate in thecase of using a substrate-processing device according to a comparativeexample to perform an oxidization process.

DETAILED DESCRIPTION OF EMBODIMENTS

Now, the embodiments of the invention will be described with referenceto the drawings. FIG. 1 shows a substrate-processing device 10 accordingto an embodiment of the invention. The substrate-processing device 10 isa vertical semiconductor manufacturing system of batch-processing type,which has a reaction furnace 12 for performing a process such as thermaloxidization on a substrate. The reaction furnace 12 has a cylindricalreaction tube 14 made of e.g. quartz with its upper end closed and thelower end opened; the reaction tube 14 forms a process chamber 16.

In the process chamber 16, a boat 18 each used as a retainer forsupporting a substrate is inserted. The boat 18 is made of e.g. quartzor silicon carbide. The boat is arranged so that it can hold wafers 20made of silicon and used as substrates in two or more sections in thestate where the substrates are kept in substantially horizontalpositions, and aligned with one another in their center positions, andhave gaps therebetween (at intervals of a substrate pitch).

The boat 18 is supported by a cylindrical heat-insulating cap 24 used asa heat-insulating member. The heat-insulating cap 24 is made of e.g.quartz or silicon carbide, and arranged so that it becomes hard totransfer the heat from a heater 30 to be described later downwards. Tothe heat-insulating cap 24, a rotation shaft 26 is attached; therotation shaft 26 extends through a seal cap 22 to be described later,and is coupled with a rotation device 28 having a driving-power source,e.g. a motor, used as a rotation means (a rotation mechanism). Therotation device 28 is fixed to the later described seal cap 22.Accordingly, a rotational driving power from the rotation device 28 istransmitted to the heat-insulating cap 24 through the rotation shaft 26,and then the heat-insulating cap 24, the boat 18, and the wafers 20 heldby the boat 18 are rotated.

In the lower end of the reaction tube 14 on the downside in thedirection of the gravity (a vertical direction), an opened portion isformed; the boat 18 is inserted into the reaction tube 14 through theopened portion. The seal cap 22 used as a lid is attached on the openedportion of the reaction tube 14 from the downside in the direction ofthe gravity. The reaction tube 14 is structured so that it ishermetically closed by the seal cap 22. The seal cap 22 is providedperpendicularly to an outer portion of the reaction tube 14, andarranged so that it can be lifted up and down by a boat elevator 40 usedas a lifting mechanism in a vertical direction. Thus, the boat 18 can bebrought into and brought out from the process chamber 16. As statedhere, when the boat elevator 40 lifts up the seal cap 22 and thus theseal cap 22 abuts against the reaction tube 14, the process chamber 16is brought to a hermetically closed state, whereas when the boatelevator 40 lifts down the seal cap 22 and thus the seal cap 22 is madeto be spaced apart from the reaction tube 14, the reaction chamber 16 isreleased from the hermetically closed state. As stated above, acombination of the boat elevator 40 and seal cap 22 is used as ahermetically-closing device for hermetically closing the process chamber16, and also used as a releasing device for releasing the processchamber 16 from the hermetically closed state.

Around the reaction tube 14, a heater 30 used as a heating means(heating mechanism) for heating the wafers 20 is disposed in a circularform concentric with the reaction tube 14. Between the reaction tube 14and the heater 30, a temperature sensor 32 used as atemperature-detecting means (temperature detector) is disposed.

On the top of the reaction tube 14 is fixed a showerhead 34, with whicha supplying line 36 composed of e.g. a piping member is coupled. On theside opposite to the side where the showerhead 34 of the supplying line36 is coupled, a reactive gas-supplying device 38 is fixed. Therefore, areactive gas supplied from the reactive gas-supplying device 38 goesthrough the supplying line 36 and reaches the showerhead 34, and thereactive gas which has reached the showerhead 34 is supplied into theprocess chamber 16 while the reactive gas is dispersed by the showerhead34. The detail of the reactive gas-supplying device 38 is to bedescribed later.

To the reaction tube 14, an exhaust line 42 composed of e.g. a pipingmember for exhausting the process chamber 16 is fixed. On the sideopposite to the exhaust line 42 of the reaction tube 14, apressure-control device 100 used as a control means (pressurecontroller) for controlling the pressure inside the process chamber 16is fixed. The detail of the pressure-control device 100 is to bedescribed later.

The reactive gas-supplying device 38 is shown in FIG. 2.

In FIG. 2( a), the reactive gas-supplying device 38 has a combustiondevice 46 such as an external combustion device. The combustion device46 is connected to the process chamber 16 (see FIG. 1) through theshowerhead 34 by the supplying line 36. The combustion device 46 isconnected with an oxygen gas source 50 formed by e.g. an oxygen tankthrough an oxygen gas-supplying line 48 composed of e.g. a pipingmember. In locations between the combustion device 46 and the oxygen gassource 50 on the oxygen gas-supplying line 48, an electromagnetic valve52 and a mass-flow controller 54 are provided in order from the side ofthe oxygen gas source 50. The electromagnetic valve 52 is used as anopening-and-closing valve for controlling supply of oxygen to thecombustion device 46/stop thereof, and the mass-flow controller 54 isused as a flow-rate controller for adjusting the flow rate of oxygensupplied to the combustion device 46.

In addition, the combustion device 46 is connected with a hydrogen gassource 58 formed by e.g. a hydrogen tank through a hydrogengas-supplying line 56 composed of e.g. a piping member. In locationsbetween the combustion device 46 and the hydrogen gas source 58 on thehydrogen gas-supplying line 56, an electromagnetic valve 60 and amass-flow controller 62 are provided in order from the side of thehydrogen gas source 58. The electromagnetic valve 60 is used forcontrolling supply of hydrogen to the combustion device 46/stop thereof,and the mass-flow controller 62 is used for adjusting the flow rate ofhydrogen supplied to the combustion device 46.

Oxygen and hydrogen are supplied from the oxygen gas source 50 and thehydrogen gas source 58 to the combustion device 46 at a given gas ratioby controlling the mass-flow controllers 54 and 62. Then, the combustiondevice 46 supplies a gas of water vapor produced by burning oxygen andhydrogen to the process chamber 16 (see FIG. 1) through the supplyingline 36 and the showerhead 34. Incidentally, oxygen which has not beenconsumed by the burning during the time is also supplied to the processchamber 16 through the supplying line 36 and the showerhead 34. Inaddition, nitrogen for dilution is supplied to the process chamber 16through the supplying line 36 and the showerhead 34 as required.

In this embodiment, an arrangement such that water vapor gas (H₂O)obtained by burning a gaseous mixture of hydrogen gas (H₂) and oxygengas (O₂) in the combustion device 46 is supplied is adopted for thereactive gas-supplying device 38. However, instead of this arrangement,the reactive gas-supplying device 38 may be arranged so as to supply agaseous mixture of oxygen and at least not less than one kind of gasselected from a group consisting of nitrogen gas (N₂), hydrogen chloride(HCl) and dichloroethylene (C₂H₂Cl₂ (abbreviated to DCE)) as shown inFIG. 2( b). Also, as shown in FIG. 2( c), the reactive gas-supplyingdevice 38 may be arranged so as to supply a gaseous mixture of oxygen(O₂) and hydrogen (H₂), and at least not less than one kind of gasselected from a group consisting of nitrogen gas (N₂), hydrogen chloride(HCl) and dichloroethylene (C₂H₂Cl₂). Now, it is noted that in FIGS. 2(b) and 2(c), 50 a, 52 a and 54 a denote a gas source of nitrogen gas(N₂), hydrogen chloride (HCl) or dichloroethylene (C₂H₂Cl₂), anelectromagnetic valve and a mass-flow controller, respectively. Also,the reactive gas-supplying device 38 may be arranged so as to supplyonly oxygen gas.

FIG. 3 shows configurations of the pressure-control device 100 and asurrounding of the pressure-control device 100. The pressure-controldevice 100 has a relative pressure gauge 113 used as a secondpressure-measuring instrument. The relative pressure gauge 113 is fixedto the exhaust line 42 through an electromagnetic valve 115, andmeasures the differential pressure between the inside pressure of theprocess chamber 16 and the outside pressure thereof. The electromagneticvalve 115 is used in an opened state normally, however it is brought toa closed state when a corrosive gas e.g. HCl is used as a reactive gas.Bringing the electromagnetic valve 115 to the closed state stops supplyof the corrosive gas to the relative pressure gauge 113, and thus therelative pressure gauge 113 is prevented from being damaged bycorrosion. In the case of using a corrosive gas in this way, therelative pressure gauge 113 is kept from contact with the corrosive gasby closing the electromagnetic valve 115 provided between the relativepressure gauge 113 and the exhaust line 42, and therefore the relativepressure gauge 113 can be prevented from being damaged by corrosion. Itis noted that using a corrosion-resistant relative pressure gauge as therelative pressure gauge 113 eliminates the need for closing theelectromagnetic valve 115 provided between the relative pressure gauge113 and the exhaust line 42, and therefore it becomes possible toconstantly monitor the differential pressure between the inside pressureof the process chamber 16 and the outside pressure thereof in the caseof using a corrosive gas.

In a location between the location of the exhaust line 42 where therelative pressure gauge 113 is fixed and the location where the exhaustline 42 is connected to the process chamber 16, a gas cooler 114 isfixed. The gas cooler 114 is used as a cooling means (cooling mechanism)for cooling a reactive gas (water vapor) exhausted from the processchamber 16, which uses a cooling water to cool the reactive gas, therebycausing condensation of the reactive gas. Unreacted gases including thereactive gas and oxygen gas, which have not been condensed by cooling bythe gas cooler 114, and nitrogen gas, are exhausted to the outside ofthe system by a pump 102, which is to be described later.

In a location downstream from the location where the gas cooler 114 ofthe exhaust line 42 is fixed and upstream from the location where therelative pressure gauge 113 is fixed, a drain line 116 is connected. Thedrain line 116 is composed of e.g. a piping member, and used to exhaustmoisture resulting from condensation of the reactive gas by the gascooler 114. The drain line 116 is connected to a drain tank 120 throughan electromagnetic valve 118. Moisture resulting from condensation ofthe reactive gas by the gas cooler 114 flows into the drain tank 120through the drain line 116, and the moisture thus having flowed into thetank is stored there. To the drain tank 120, a discharge line 121 isconnected so as to be located, for example, below the drain tank 120 inthe direction of the gravity. To the discharge line 121 is fixed anelectromagnetic valve 122. The moisture discharged into the drain tank120 can be stored by bringing the electromagnetic valve 122 to theclosed state, and the moisture stored in the drain tank 120 isdischarged to the outside of the system by bringing the electromagneticvalve 122 to the opened state. Incidentally, the discharge of themoisture stored in the drain tank 120 to the outside of the system isperformed by closing the electromagnetic valve 118 and opening theelectromagnetic valve 122 after the pressure inside the process chamber16 has been returned to a atmospheric pressure after oxidization of awafer.

At a location on the exhaust line 42 between the location where the gascooler 114 is fixed and the process chamber 16, an atmosphericpressure-vent line 124 composed of e.g. a piping member is fixed. Theatmospheric pressure-vent line 124 allows a portion of the exhaust line42 upstream from the gas cooler 114 and a portion of the exhaust line 42downstream from the pump 102 to communicate with each other through theelectromagnetic valve 126. When the relative pressure gauge 113 measuresa pressure of the inside of the process chamber 16, and the measurementis positive with respect to the pressure of the outside of the chamber,the electromagnetic valve 126 is brought to the opened state thereby torelease the pressure inside the reaction chamber 16 through theatmospheric pressure-vent line 124, and to prevent an overpressure frombeing applied to the inside of the reaction chamber 16. The upstream endof the atmospheric pressure-vent line 124 may be connected to a stagebehind the gas cooler 114 (downstream from the gas cooler 114) of theexhaust line 42, e.g. a portion of the drain line 116 upstream from theelectromagnetic valve 118. The following are made possible by making thearrangement like this: to lower the temperature of a heated gasdischarged from the atmospheric pressure-vent line 124 in using theatmospheric pressure-vent line 124 to exhaust; and to prevent a heatedgas from adversely affecting the atmospheric pressure-vent line 124, avicinity of a connection of the exhaust line 42 with the downstream endof the atmospheric pressure-vent line 124, and members constituting theexhaust line 42 and others downstream from the connection.

When the substrate-processing device 10 having only the relativepressure gauge 113 as stated above is used to form an oxide film on awafer 20, the differential pressure between the inside pressure of theprocess chamber 16 and the outside pressure thereof are gauged by therelative pressure gauge 113. Then, an adjustment is made based on theresult of the gauging so that the inside pressure of the process chamber16 is lower than the outside pressure thereof by a fixed value at alltimes. Also, an adjustment is made to make the pressure inside theexhaust line 42 lower than that inside the process chamber 16constantly. When making the inside pressure of the process chamber 16lower than the outside pressure thereof in this way, it becomes harderfor the reactive gas in the process chamber 16 to leak form the insideof the process chamber 16 to the outside of the process chamber 16. Inaddition, when making the pressure inside the exhaust line 42 lower thanthe inside pressure of the process chamber 16 in this way, the gas canbe prevented from flowing backward from the side of the exhaust line 42into the process chamber 16, and therefore a stable oxidization processcan be achieved in the process chamber 16.

The substrate-processing device 10 having only the relative pressuregauge 113 adjusts the pressure inside the process chamber 16 based on aresult of gauging by the relative pressure gauge 113 as stated above.However, the substrate-processing device regulates the internal pressureof the process chamber 16 so that the difference between the insidepressure of the process chamber 16 and the pressure of the outside ofthe process chamber 16 is constant, and therefore when the change in theatmospheric pressure owing to e.g. a climate change causes thefluctuation in the pressure of the outside of the process chamber 16,the inside pressure of the process chamber 16 is also changed dependingon the change. In addition, there is a problem that the change in thepressure inside the process chamber 16 causes the variation in thicknessof the oxide film formed on a wafer 20. In the case like this, it isneeded to adjust the thickness by adjusting the time for the oxidizationprocess or doing something like that.

Therefore, as to the substrate-processing device 10 according to thisembodiment, better ways to make an arrangement for measuring the insidepressure of the process chamber 16 and to control thesubstrate-processing device 10 based on the result of the measurement ofthe pressure inside the process chamber 16 are devised, thereby reducingthe tendency to cause the variation in thickness of the oxide film owingto that the pressure inside the process chamber 16 is not kept constant.In addition, in regard to the substrate-processing device according tothe embodiment, better ways to make an arrangement for measuring thepressure inside the process chamber 16 and to control thesubstrate-processing device 10 based on the result of the measurement ofthe pressure inside the process chamber 16 are devised, thereby reducingthe tendency of the gas to leak out from the process chamber 16.

As shown in FIG. 3, a pump 102 used as an exhausting means (exhaustingdevice) for exhausting the process chamber 16 is provided in a locationon the exhaust line 42 downstream from the location where the relativepressure gauge 113 is fixed. The pump 102 is composed of e.g. a vacuumpump, and has a venturi tube therein. To the venturi tube, a nitrogengas source 106 used as a fluid-supplying means for supplying a fluid tothe venturi tube is connected through e.g. a nitrogen-supplying line 108composed of a piping member, etc. Between the nitrogen gas source 106and the pump 102 on the nitrogen-supplying line 108, a regulator 110 andan electromagnetic valve 112 are provided in order from the side of thenitrogen gas source 106.

The regulator 110 is used to adjust the pressure of the nitrogen gassupplied to the venturi tube of the pump 102 to be a constant pressure,thereby regulating the flow rate of the nitrogen gas, and the pressureinside the process chamber 16 can be lowered below the atmosphericpressure by controlling the outflow rate of the exhaust gas led out fromthe process chamber 16 into the pump.

In a location on the exhaust line 42 downstream from the location wherethe relative pressure gauge 113 is fixed and upstream from the locationwhere the pump 102 is fixed, an absolute pressure-control device 130 isfixed. The absolute pressure-control device 130 is used as a firstpressure-measuring instrument, and has an absolute pressure gauge 132for measuring the pressure inside the process chamber 16. The absolutepressure gauge 132 has a pressure-measurement point located in thevicinity of a pressure-measurement point of the relative pressure gauge113.

The relative pressure gauge 113 measures the differential pressurebetween the inside pressure of the process chamber 16 and the outsidepressure thereof as stated above, and exactly it measures thedifferential pressure (relative pressure) between an exhaust pressureinside the exhaust line 42 and a an atmospheric pressure of the outsideof the process chamber 16 when the process chamber 16 is exhausted. Theabsolute pressure gauge 132 measures the inside pressure of the processchamber 16, and exactly it measures an exhaust pressure (absolutepressure) inside the exhaust line 42 when the process chamber 16 isexhausted. Now, it can be thought that a pressure loss is produced bythe gas cooler 114, etc. provided between the pressure-measurementpoints inside the process chamber 16 and exhaust line 42, and thereforea pressure difference of about 50 to 100 Pa is developed. Hence, thepressure inside the process chamber 16 can be thought to be somewhathigher than the pressure of at the pressure-measurement point in theexhaust line 42 by the pressure loss attributed to the gas cooler 114,etc. and the control of the pressure inside the process chamber 16 isperformed in consideration of this.

The absolute pressure-control device 130 is connected through thenitrogen-supplying line 134 and the nitrogen-supplying line 108 to theaforementioned nitrogen gas source 106. Specifically, thenitrogen-supplying line 134 branches out form the nitrogen-supplyingline 108 at a location closer to the pump 102 in comparison to theelectromagnetic valve 112. The nitrogen-supplying line 134 connectsbetween the absolute pressure-control device 130 and the nitrogen gassource 106. On the nitrogen-supplying line 134, a regulator 136 isprovided, which adjusts the pressure of nitrogen gas supplied to theabsolute pressure-control device 130 to be a constant pressure therebyto regulate the flow rate of the nitrogen gas. The nitrogen gas suppliedto the absolute pressure-control device 130 from the nitrogen gas source106 is used to drive a pressure-adjusting valve 133 for adjusting thepressure of the process chamber 16, which is provided in the absolutepressure-control device 130.

A controller 200 that the substrate-processing device 10 has is shown inFIG. 4. The controller 200 has a control circuit 202; the controlcircuit 202 has a temperature-control module 204, a supply-controlmodule 206, a pressure-control module 208, a driving-control module 210,and a warning-generation module 230. Also, the control circuit 202 has amain control module 212 for controlling the temperature-control module204, the supply-control module 206, the pressure-control module 208, thedriving-control module 210, and the warning-generation module 230. Tothe control circuit 202, signals from the temperature sensor 32, therelative pressure gauge 113, and the absolute pressure gauge 132 areinput. According to outputs from the control circuit 202, the heater 30,the reactive gas-supplying device 38, the pressure-control device 100,the rotation device 28, the boat elevator 40, and the warning device 231are controlled.

Next, a method of using the substrate-processing device 10 inassociation with the arrangement as described above to perform anoxidization process on a wafer 20 as a step of a manufacturing processof a semiconductor device (device) will be described. It is noted thatin the description below actions of respective modules which constitutethe substrate-processing device 10 are controlled by the controller 200.FIG. 5 shows a control flow of a wafer oxidization process according tothe controller 200. First, in Step S10 the controller 200 controls theboat elevator 40 and makes the boat elevator lift up the boat 18 holdingwafers 20 into the process chamber 16, thereby to bring (load) thewafers 20 into the process chamber 16. At the time when loading of thewafers 20 into the process chamber 16 is completed, the reaction tube 14is in the state where it is hermetically closed by the seal cap 22.

In the subsequent Step S12, the controller 200 controls thepressure-control device 100 to keep constant the inside pressure of theprocess chamber 16. Specifically, while using the pump 102 to exhaustthe process chamber 16 to a vacuum condition, the controller 200measures the exhaust pressure with the absolute pressure gauge 132 andperforms feedback control of the pressure-adjusting valve 133 based on asignal input from the absolute pressure gauge 132, thereby to controlthe flow rate of the exhaust gas discharged from the process chamber 16and to control the inside pressure of the process chamber 16.Incidentally, in parallel with the control of the pressure inside theprocess chamber 16, the controller 200 performs the control as describedlater based on a signal input from the relative pressure gauge 113.

In the pressure control of Step S12, the control is exercised so thatthe inside pressure of the process chamber 16 is made a pressure a bitlower than a minimum air pressure in fluctuations of atmospherethroughout the year. Concretely, the inside of the process chamber 16 iscontrolled to be at a pressure equal to or below 1000 hPa (hectopascal),which is a bit lower than an atmospheric pressure (i.e. slightly reducedpressure). Also, the inside of the process chamber 16 is controlled tobe at a pressure equal to or above 800 hPa so as to prevent the reactiontube 14 made of quartz from being damaged.

Now, it is assumed originally that the system targeted in the embodimentof the invention is used under a pressure near the atmospheric pressure,and therefore a pressure below 800 hPa can cause damage to the reactiontube. In this respect, the reaction tube is different from a CVDreaction tube adapted for a reduced pressure such that e.g. a measurefor dispersing a stress is taken by making the ceiling of the reactiontube round. Therefore, in this embodiment, the inside pressure of theprocess chamber 16 is controlled so as to be equal to or above 800 hPa.That is, the control is performed so that the inside of the processchamber 16 is at a pressure in a range of 800 to 1000 hPa.

It is preferable that the inside of the process chamber 16 is controlledto be at a pressure in a pressure range of 900 to 980 hPa. Controllingthe inside of the process chamber 16 to be at 900 to 980 hPa allowscombustion by the combustion device 46 to be continued well during theoxidization involving the ignition and burning reaction of hydrogen andoxygen as in this embodiment, i.e. pyrogenic oxidization.

In this way, the controller 200 performs control so that the pressureinside the process chamber 16 is kept constant, based on not thedifferential pressure between the inside pressure of the process chamber16 and the outside pressure thereof, namely the relative pressure, butthe inside pressure of the process chamber 16, namely the absolutepressure. Therefore, even when the pressure of the outside of theprocess chamber 16 is changed owing to e.g. a climate change, etc., theinside pressure of the process chamber 16 is not affected by it and thechange thereof is not caused. Hence, the variation in the thickness of aformed film as caused when the pressure inside the process chamber 16 isnot kept constant does not arise. This eliminates the need for adjustingthe thickness of a film by adjustment of the process time foroxidization, and therefore the time for oxidization can be madeconstant. This can prevent the occurrence of a slight difference inrearrangement of impurities between wafers 20, which is caused by thechange in diffusion lengths of impurities resulting from the change inthermal hysteresis with respect to the wafers 20 when the time foroxidization varies from batch to batch. The control of the pressure ofthe inside of the reaction chamber 16 is performed continuously untilthe rotation of the wafers 20 is stopped in Step S20.

In the subsequent Step S14, the controller 200 performs feedback controlof the heater 30 based on a signal from the temperature sensor 32thereby to keep the temperature inside the process chamber 16substantially constant.

In the subsequent Step S16, the controller 200 controls the rotationdevice 28 to make the wafers 20 put in the process chamber 16 startrotation.

In the subsequent Step S18, the controller 200 controls the reactivegas-supplying device 38 to make the reactive gas-supplying device 38supply the reactive gas to the process chamber 16. Specifically, thecontroller 200 controls the mass-flow controllers 54 and 62 thereby tohave oxygen and hydrogen supplied to the combustion device 46 at adesired rate and to have water vapor supplied from the combustion device46 to the process chamber 16. In this time, oxygen which has not beenconsumed by the combustion is also supplied into the process chamber 16.In addition, as required, the nitrogen for dilution is also suppliedinto the process chamber 16. The water vapor and oxygen to be suppliedto the process chamber 16 are diffused by the showerhead 34 and reachsurfaces of the wafers 20 in the state, to form oxide films on thesurfaces of the wafers 20.

In the subsequent Step S20, the controller 200 controls the reactivegas-supplying device 38 to have the supply of the reactive gas to theprocess chamber 16 stopped, and controls the rotation device 28 to havethe rotation of the wafers 20 stopped. Thereafter nitrogen is suppliedto the process chamber 16 and the inside of the process chamber 16 ispurged, and then the inside of the process chamber 16 is returned to theatmospheric pressure. In this time, the inside of the process chamber 16is returned to the atmospheric pressure while the differential pressurebetween the inside pressure of the process chamber 16 and the outsidepressure thereof is sensed by the relative pressure gauge 113.

In the subsequent Step S22, the controller 200 controls the boatelevator 40 to have the wafers 20, which are left supported by the boat18 after completion of the oxidization process, brought out (unloaded)from the process chamber 16. It is noted that when in Step S22, a signalshowing that the pressure difference between the inside and outside ofthe process chamber 16 is equal to or above a predetermined value, i.e.out of an allowable range has been input from the relative pressuregauge 113, the controller 200 prohibits the boat elevator 40 from beingdriven thereby to make it impossible to bring out the wafers 20 from theprocess chamber 16. In other words, it is prohibited to free the processchamber 16 from the hermetically closed state. Only in the case where asignal showing the pressure difference between the inside and outside ofthe process chamber 16 is below the predetermined value, i.e. within theallowable range has been input from the relative pressure gauge 113, thecontroller 200 allows the boat elevator 40 to be driven, thereby toenable the wafers 20 to be brought out from the process chamber 16. Inother words, it is allowed to free the process chamber 16 from thehermetically closed state. In the case where there is the pressuredifference between the inside and outside of the process chamber 16,this control can reduce the tendency of a rapid change in the pressureinside the process chamber 16 in taking out the wafers 20 from theprocess chamber 16 to damage the boat 18 and generate particles.

In the step of supplying the reactive gas of Step S18, when the insidepressure of the process chamber 16 is higher than the outside pressurethereof, the inside of the process chamber 16 is put in a pressurizedstate, posing the risk of causing leakage of the gas. Hence, in thesubstrate-processing step until the rotation of the wafers 20 is stoppedin Step S20 since the adjustment of the pressure of the process chamber16 is made in Step S12, when a signal showing that the inside pressureof the process chamber 16 is higher than the outside pressure thereof isinput from the relative pressure gauge 113, the controller 200 preventsthe electromagnetic valve 52 and electromagnetic valve 60 from beingopened thereby to make it impossible to supply the process chamber 16with water vapor if the valves are in the closed state. If theelectromagnetic valve 52 and the electromagnetic valve 60 have beenopened, the controller 200 brings the valves to their closed states tostop the supply of water vapor to the process chamber 16 thereby to stopprocessing the substrates. However, as long as a signal showing that theinside pressure of the process chamber 16 is lower than the outsidepressure thereof is input from the relative pressure gauge 113 in thesubstrate-processing steps of Step S12 to Step S20, the controller 200retains the electromagnetic valve 52 and the electromagnetic valve 60 ina condition that they can be brought to the opened state, and thereforemaintains a condition that the reactive gas can be supplied from thereactive gas-supplying device 38 to the process chamber 16.

As stated above, the substrate-processing device 10 according to theembodiment is arranged so that the supply of the reactive gas is enabledonly when the inside of the process chamber 16 is negative in pressurerelative to the outside thereof by using the relative pressure gauge 113to monitor the pressure difference between the inside and outside of theprocess chamber 16, and therefore the substrate-processing device usesthe relative pressure gauge 113 as an interlock trigger. The cases wherethe inside pressure of the process chamber 16 is higher than the outsidepressure thereof include a case such that the atmospheric pressure dropsrapidly owing to the fluctuation in the atmospheric pressure, etc. belowthe pressure inside the process chamber 16.

In this embodiment, the substrate-processing device is arranged so thatwater vapor, which is a reactive gas, cannot be supplied into theprocess chamber 16 when the inside pressure of the process chamber 16 ishigher than the outside pressure thereof. However, water vapor has notoxicological property, and even if the water vapor somewhat leaks frominside the process chamber 16 to the outside, it causes no harm.Therefore, in the case of using a gas having no toxicological propertylike water vapor, even if the inside pressure of the process chamber 16is higher than the outside pressure thereof, it is not necessary todisable the supply of the reactive gas into the process chamber 16.

In contrast, in the cases of using gases having corrosive and toxicproperties, such as NO, No_(x), N₂O, NH₃, DCE and HCl, it is necessaryto reliably prevent the gases from leaking from the inside of theprocess chamber 16 to the outside. It becomes indispensable to precludesupply of a reactive gas into the process chamber 16 when the insidepressure of the process chamber 16 is higher than the outside pressurethereof.

In addition, the substrate-processing device may be arranged so that inthe substrate-processing steps of Step S12 to Step S20, when a signalshowing that the inside pressure of the process chamber 16 is higherthan the outside pressure thereof is input from the relative pressuregauge 113, the controller 200 controls the warning-generation module 230to make the warning device 231 generate a warning. As the warning device231 may be used e.g. a sound-producing device which produces a warningsound and a light-emitting device which emits a warning light.

FIG. 6 shows the relation between the pressure of the outside of theprocess chamber 16 and the film thickness of an oxide film formed on awafer 20 in the case of using the substrate-processing device 10according to the embodiment of the invention to perform an oxidizationprocess. The horizontal axis shows the pressure of the outside of theprocess chamber 16 (hPa), and the vertical axis shows the film thickness(Angstrom) of a film formed on each wafer. In the horizontal axis ofFIG. 6, the three pieces of data denoted by Condition A (A1, A2, A3)each show a film thickness of a film formed on a wafer 200 when thepressure of the outside of the process chamber 16 is 1006.8 hPa; A1, A2and A3 show film thicknesses of films formed on wafers 20 disposed in anupper portion, a center portion and a lower portion of the processchamber 16, respectively.

Likewise, the pieces of data denoted by Condition B (B1, B2, B3) eachshow a film thickness of a film formed on a wafer 20 when the pressureof the outside of the process chamber 16 is 1003.0 hPa; B1, B2 and B3show film thicknesses of films formed on wafers 20 disposed in theupper, center and lower portions of the process chamber 16,respectively. Further, likewise, the pieces of data denoted by ConditionC (C1, C2, C3) each show a film thickness of a film formed on a wafer 20when the pressure of the outside of the process chamber 16 is 993.7 hPa;C1, C2 and C3 show film thicknesses of films formed on wafers 20disposed in the upper, center and lower portions of the process chamber16, respectively. Now, it is noted that the pressure of the outside ofthe process chamber of the horizontal axis shows the fluctuation in theatmospheric pressure.

As is clear from the data shown in FIG. 6, even when the pressure of theoutside of the process chamber 16, namely the atmospheric pressurefluctuates, the fluctuation in film thickness between the data orbatches is suppressed to 0.17 percent.

FIG. 7 shows the relation between the pressure of the outside of theprocess chamber 16 and the film thickness of an oxide film formed oneach wafer 20 in the case of using a substrate-processing deviceaccording to a comparative example to process substrates. The verticalaxis of the right side shows the pressure of the outside of the processchamber (mmHg), and the vertical axis of the left side shows the filmthickness of a film formed on each wafer (Angstrom). In thesubstrate-processing device 10 according to the embodiment, the insidepressure of the process chamber 16 is controlled based on results ofmeasurements by the absolute pressure gauge 132 while consideringresults of measurements by the relative pressure gauge 113. In contrast,the substrate-processing device according to the comparative examplecontrols the pressure of the process chamber 16 based on only results ofmeasurements by the relative pressure gauge 113. In other words, thesubstrate-processing device performs control based on results ofmeasurements by the relative pressure gauge 113 so that the insidepressure of the process chamber 16 is lower than the outside pressurethereof by a fixed value.

In FIG. 7, D denotes the pressures of the outside of the process chamber16 in Conditions 1 to 10, i.e. the fluctuation in the atmosphericpressure. E1, E2 and E3 show film thicknesses of films formed on wafers20 disposed in the upper, center and lower portions of the processchamber 16 in Conditions 1 to 10, respectively. It is clear from FIG. 7that in the substrate-processing device in association with thecomparative example, the film thickness is increased when theatmospheric pressure is higher, and it decreased when the atmosphericpressure is lower, the film thickness of a film formed on each wafer 20varies depending on the change in the pressure of the outside of theprocess chamber 16, i.e. the change in the atmospheric pressure, and thevariation reaches up to 2.5 percent.

Now, the preferred embodiments of the invention will be described.

According to an embodiment of the invention is provided a substrateprocessing apparatus comprising: a process chamber for processing asubstrate; a reactive gas-supplying module for supplying a reactive gasinto the process chamber; a reactive gas-supplying line for supplyingthe reactive gas from the reactive gas-supplying module into the processchamber; an exhaust line for exhausting an inside of the processchamber; a pump provided in the exhaust line for vacuumizing the insideof the process chamber; a pressure-adjusting valve provided in theexhaust line for adjusting a pressure in the process chamber; a firstpressure-measuring instrument for measuring an inside pressure of theprocess chamber; a second pressure-measuring instrument for measuring adifferential pressure between the inside pressure of the process chamberand an outside pressure thereof; and a controller which controls thepressure-adjusting valve based on a value of the inside pressure of theprocess chamber measured by the first pressure-measuring instrument soas to keep the inside pressure of the process chamber constant, andcontrols the reactive gas-supplying module based on a value of thedifferential pressure measured by the second pressure-measuringinstrument so as to allow supply of the reactive gas into the processchamber in a case of the inside pressure of the process chamber beingsmaller than the outside pressure thereof, and so as to preclude supplyof the reactive gas into the process chamber in a case of the insidepressure of the process chamber being larger than the outside pressurethereof when processing the substrate.

It is preferable that the controller controls the reactive gas-supplyingmodule so that a gaseous mixture composed of O₂ gas and at least notless than one kind of gas selected from a group consisting of H₂O gas,which can be obtained by burning H₂ gas and O₂ gas, N₂ gas, HCl gas,C₂H₂Cl₂ gas and H₂ gas, or only O₂ gas is supplied into the processchamber as the reactive gas when processing the substrate.

It is preferable that the controller controls the reactive gas-supplyingmodule so that a gas containing a corrosive or toxic gas is suppliedinto the process chamber as the reactive gas when processing thesubstrate.

It is preferable that the controller controls the pressure-adjustingvalve so that the inside pressure of the process chamber is kept aconstant pressure within a range of 800 to 1000 hPa when processing thesubstrate.

It is preferable that the controller controls the pressure-adjustingvalve so that the inside pressure of the process chamber is kept aconstant pressure within a range of 900 to 980 hPa when processing thesubstrate.

It is preferable that the controller further performs control based onthe value of the differential pressure measured by the secondpressure-measuring instrument so that the inside of the process chamberis allowed to be opened when the differential pressure falls within anallowable range, and opening the inside of the process chamber isprecluded when the differential pressure falls outside the allowablerange after the processing of the substrate.

It is preferable that the controller further performs control based onthe value of the differential pressure measured by the secondpressure-measuring instrument so that the processed substrate is allowedto be brought out from inside the process chamber when the differentialpressure falls within an allowable range, and the processed substrate isprecluded from being brought out from inside the process chamber whenthe differential pressure falls outside the allowable range after theprocessing of the substrate.

It is preferable that the substrate processing apparatus has: a supporttool for supporting the substrate in the process chamber; a lid forsupporting the support tool and hermetically closing an opened portionof the process chamber to take in and out the support tool; and alifting mechanism for lifting up and down the lid thereby to lift up anddown the support tool, wherein the controller further performs controlbased on the value of the differential pressure measured by the secondpressure-measuring instrument so that the lifting mechanism is allowedto be driven when the differential pressure falls within an allowablerange, and the lifting mechanism is prohibited from being driven whenthe differential pressure falls outside the allowable range after theprocessing of the substrate.

According to another embodiment of the invention is provided a substrateprocessing apparatus comprising: a process chamber for processing asubstrate; a reactive gas-supplying line for supplying a reactive gasinto the process chamber; an exhaust line for exhausting an inside ofthe process chamber; a pump provided in the exhaust line for vacuumizingthe inside of the process chamber; a pressure-adjusting valve providedin the exhaust line for adjusting a pressure in the process chamber; afirst pressure-measuring instrument for measuring an inside pressure ofthe process chamber; a second pressure-measuring instrument formeasuring a differential pressure between the inside pressure of theprocess chamber and an outside pressure thereof; a lid for hermeticallyclosing an opened portion of the process chamber to take in and out thesubstrate; and a controller which controls the pressure-adjusting valvebased on a value of the inside pressure of the process chamber measuredby the first pressure-measuring instrument so as to keep the insidepressure of the process chamber constant when processing the substrate,and after the processing of the substrate, performs control based on thevalue of the differential pressure measured by the secondpressure-measuring instrument so that release of the hermeticallyclosing by the lid is allowed when the differential pressure fallswithin an allowable range, and so that release of the hermeticallyclosing by the lid is precluded when the differential pressure fallsoutside the allowable range.

According to still another embodiment of the invention is provided amethod of manufacturing a semiconductor device comprising the steps of:bringing a substrate into a process chamber; processing the substratewhile supplying a reactive gas into the process chamber with thesubstrate brought therein and vacuumizing inside the process chamber;and bringing out the processed substrate from the process chamber,wherein in the step of processing the substrate, an inside pressure ofthe process chamber is measured, and in parallel, the inside pressure ofthe process chamber is kept constant based on a measurement thereof, anda differential pressure between the inside pressure of the processchamber and an outside pressure thereof, and based on a measurementthereof is measured, the reactive gas is supplied into the processchamber when the inside pressure of the process chamber is smaller thanthe outside pressure thereof, and the reactive gas is not supplied intothe process chamber when the inside pressure of the process chamber islarger than the outside pressure thereof.

Further, according to another embodiment of the invention is provided amethod of manufacturing a semiconductor device comprising the steps of:bringing a substrate into a process chamber; processing the substratewhile supplying a reactive gas into the process chamber with thesubstrate brought therein and vacuumizing inside the process chamber;and bringing out the processed substrate from the process chamber,wherein in the step of processing the substrate, an inside pressure ofthe process chamber is measured, and in parallel, the inside pressure ofthe process chamber is kept constant based on a measurement thereof, andafter the processing of the substrate, a differential pressure betweenthe inside pressure of the process chamber and an outside pressurethereof is measured, and based on a measurement thereof, the step ofbringing out the processed substrate is executed when the differentialpressure falls within an allowable range, whereas when the differentialpressure falls outside the allowable range, the step of bringing out theprocessed substrate is not executed.

As stated above, the invention can be utilized for asubstrate-processing device and a method of manufacturing asemiconductor device, which are for performing a process such asoxidization of a surface of a substrate composed of a semiconductorwafer, a glass substrate or the like.

1. A substrate processing apparatus comprising: a process chamber foroxidizing of a substrate; a water vapor gas-supplying module forsupplying a water vapor gas into the process chamber; a water vaporgas-supplying line for supplying the water vapor gas from the watervapor gas-supplying module into the process chamber; an exhaust line forexhausting an inside of the process chamber; a pump provided in theexhaust line for vacuumizing the inside of the process chamber; apressure-adjusting valve provided in the exhaust line for adjusting apressure in the process chamber; a first pressure-measuring instrumentfor measuring an inside pressure of the process chamber; a secondpressure-measuring instrument for measuring a differential pressurebetween the inside pressure of the process chamber and an outsidepressure thereof; and a controller which controls the pressure-adjustingvalve based on a value of the inside pressure of the process chambermeasured by the first pressure-measuring instrument so as to keep theinside pressure of the process chamber constant, and controls the watervapor gas-supplying module based on a value of the differential pressuremeasured by the second pressure-measuring instrument so as to allowsupply of the water vapor gas into the process chamber in a case of theinside pressure of the process chamber being smaller than the outsidepressure thereof.
 2. The substrate processing apparatus according toclaim 1, wherein the water vapor gas-supplying module has: a combustiondevice for obtaining the water vapor gas by burning a gaseous mixture ofhydrogen gas and oxygen gas.
 3. The substrate processing apparatusaccording to claim 1, wherein the controller controls thepressure-adjusting valve so that the inside pressure of the processchamber is kept a constant pressure within a range of 800 to 1000 hPawhen processing the substrate.
 4. The substrate processing apparatusaccording to claim 1, wherein the controller controls thepressure-adjusting valve so that the inside pressure of the processchamber is kept a constant pressure within a range of 900 to 980 hPawhen processing the substrate.
 5. A substrate processing apparatuscomprising: a process chamber for processing a substrate; a reactivegas-supplying module for supplying a reactive gas having corrosive ortoxic properties into the process chamber; a reactive gas-supplying linefor supplying the reactive gas having corrosive or toxic properties fromthe reactive gas-supplying module into the process chamber; an exhaustline for exhausting an inside of the process chamber; a pump provided inthe exhaust line for vacuumizing the inside of the process chamber; apressure-adjusting valve provided in the exhaust line for adjusting apressure in the process chamber; a first pressure-measuring instrumentfor measuring an inside pressure of the process chamber; a secondpressure-measuring instrument for measuring a differential pressurebetween the inside pressure of the process chamber and an outsidepressure thereof; a warning device for generating a warning; and acontroller which controls the pressure-adjusting valve based on a valueof the inside pressure of the process chamber measured by the firstpressure-measuring instrument so as to keep the inside pressure of theprocess chamber constant, and controls the warning device based on avalue of the differential pressure measured by the secondpressure-measuring instrument so as to generate the warning in a case ofthe inside pressure of the process chamber being larger than the outsidepressure thereof.
 6. A method of manufacturing a semiconductor devicecomprising the steps of: bringing a substrate into a process chamber;oxidizing the substrate while supplying a water vapor gas into theprocess chamber with the substrate brought therein and vacuumizinginside the process chamber; and bringing out the oxidized substrate fromthe process chamber, wherein in the step of oxidizing the substrate, aninside pressure of the process chamber is measured, and in parallel, theinside pressure of the process chamber is kept constant based on ameasurement thereof, and a differential pressure between the insidepressure of the process chamber and an outside pressure thereof ismeasured, and based on a measurement thereof, the water vapor gas issupplied into the process chamber when the inside pressure of theprocess chamber is smaller than the outside pressure thereof.
 7. Amethod of manufacturing a semiconductor device comprising the steps of:bringing a substrate into a process chamber; processing the substratewhile supplying a reactive gas having corrosive or toxic properties intothe process chamber with the substrate brought therein and vacuumizinginside the process chamber; and bringing out the processed substratefrom the process chamber, wherein in the step of processing thesubstrate, an inside pressure of the process chamber is measured, and inparallel, the inside pressure of the process chamber is kept constantbased on a measurement thereof, and a differential pressure between theinside pressure of the process chamber and an outside pressure thereofis measured, and based on a measurement thereof, a warning is generatingwhen the inside pressure of the process chamber is larger than theoutside pressure thereof.
 8. A method of processing a substratecomprising the steps of: bringing a substrate into a process chamber;oxidizing the substrate while supplying a water vapor gas into theprocess chamber with the substrate brought therein andvacuumizing-inside the process chamber; and bringing out the oxidizedsubstrate from the process chamber, wherein in the step of oxidizing thesubstrate, an inside pressure of the process chamber is measured, and inparallel, the inside pressure of the process chamber is kept constantbased on a measurement thereof, and a differential pressure between theinside pressure of the process chamber and an outside pressure thereofis measured, and based on a measurement thereof, the water vapor gas issupplied into the process chamber when the inside pressure of theprocess chamber is smaller than the outside pressure thereof.
 9. Amethod of processing a substrate comprising the steps of: bringing asubstrate into a process chamber; processing the substrate whilesupplying a reactive gas having corrosive or toxic properties into theprocess chamber with the substrate brought therein and vacuumizinginside the process chamber; and bringing out the processed substratefrom the process chamber, wherein in the step of processing thesubstrate, an inside pressure of the process chamber is measured, and inparallel, the inside pressure of the process chamber is kept constantbased on a measurement thereof, and a differential pressure between theinside pressure of the process chamber and an outside pressure thereofis measured, and based on a measurement thereof, a warning is generatingwhen the inside pressure of the process chamber is larger than theoutside pressure thereof.